A zinc oxide-modified hydroxyapatite-based cement facilitated new crystalline-stoichiometric and amorphous apatite precipitation on dentine

Abstract

Aim

To evaluate the remineralization ability of two endodontic sealer cements.

Methodology

Mid-coronal dentine surfaces were subjected to: i) 37% phosphoric acid (PA) or ii) 0.5 M ethylenediaminetetraacetic acid (EDTA) conditioning prior to the application of two experimental hydroxyapatite-based cements, containing sodium hydroxide (calcypatite) or zinc oxide (oxipatite), respectively. Samples were stored in simulated body fluid for 24 h or 21 d. Remineralization of the dentine surfaces were studied by Raman spectroscopy (mapping with K-means cluster and hierarchical cluster analysis) was undertaken were done. Nano-roughness and collagen fibrils width measurements were performed with an atomic force microscopy. ANOVA and Student-Newman-Keuls were performed (α=0.05).

Results

PA+oxipatite promoted both the highest dentine mineralization (p<0.05) and crystallographic maturity at the dentin surface. Non-crystalline amorphous-like apatites were also formed. Dentine treated with PA+calcypatite attained the roughest surface (p<0.05) with minimal fibril width (p<0.05). Crosslinking of collagen only became greater in the group PA+oxipatite, after 21 d. The maximum relative mineral concentration and structure of collagen concerning to amide I and ratio amide III/AGEs was obtained after using PA+calcypatite at 21 d time point (p<0.05). EDTA produced a lower stoichiometric hydroxyapatite (p<0.05) with decreased maturity, at the expense of the carbonate band widening, though it favored the nucleation of carbonated calcium phosphate.

Conclusions

Dentine surfaces treated with PA+oxipatite attained the highest dentine remineralization with both crystalline-stoichiometric and amorphous apatites, at 21 d. EDTA conditioning facilitated amorphous-bulk mineral precipitation. The amorphization, was more intense after using oxipatite and provided an ion-rich environment favoring in situ dentine remineralization.

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